到19世纪中叶的时候，科学家对被称为电磁力这一现象中三个组成部分(指电、磁和光，译者注)已经有了相当的了解。

By the mid-19th century scientists had a fair understanding of each of the three components of electromagnetism, as the phenomenon has come to be called.

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布罗克斯说，更为重要的是，有一种“三指蛋白质”可以视为“局部进化的关键性例子”。

What’s more, it’s a kind of protein — calleda three-finger protein — that is involved in other “striking examplesof local evolution, ” Brockes says.

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广告业界有“三块屏幕”的说法，这三块屏幕指的就是电视屏幕、互联网电脑屏幕和手机屏幕。

You now hear talk in the advertising trade of our “three screens”: television, the Internet and mobile devices.

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